@misc{FranckDabrowskiSchubertetal., author = {Franck, Max and Dabrowski, Jaroslaw and Schubert, Markus Andreas and Wenger, Christian and Lukosius, Mindaugas}, title = {Towards the Growth of Hexagonal Boron Nitride on Ge(001)/Si Substrates by Chemical Vapor Deposition}, series = {Nanomaterials}, volume = {12}, journal = {Nanomaterials}, number = {19}, issn = {2079-4991}, doi = {10.3390/nano12193260}, abstract = {The growth of hexagonal boron nitride (hBN) on epitaxial Ge(001)/Si substrates via high-vacuum chemical vapor deposition from borazine is investigated for the first time in a systematic manner. The influences of the process pressure and growth temperature in the range of 10-7-10-3 mbar and 900-980 °C, respectively, are evaluated with respect to morphology, growth rate, and crystalline quality of the hBN films. At 900 °C, nanocrystalline hBN films with a lateral crystallite size of ~2-3 nm are obtained and confirmed by high-resolution transmission electron microscopy images. X-ray photoelectron spectroscopy confirms an atomic N:B ratio of 1 ± 0.1. A three-dimensional growth mode is observed by atomic force microscopy. Increasing the process pressure in the reactor mainly affects the growth rate, with only slight effects on crystalline quality and none on the principle growth mode. Growth of hBN at 980 °C increases the average crystallite size and leads to the formation of 3-10 well-oriented, vertically stacked layers of hBN on the Ge surface. Exploratory ab initio density functional theory simulations indicate that hBN edges are saturated by hydrogen, and it is proposed that partial de-saturation by H radicals produced on hot parts of the set-up is responsible for the growth}, language = {en} } @misc{FranckDabrowskiSchubertetal., author = {Franck, Max and Dabrowski, Jarek and Schubert, Markus Andreas and Vignaud, Dominique and Achehboune, Mohamed and Colomer, Jean-Fran{\c{c}}ois and Henrard, Luc and Wenger, Christian and Lukosius, Mindaugas}, title = {Investigating Impacts of Local Pressure and Temperature on CVD Growth of Hexagonal Boron Nitride on Ge(001)/Si}, series = {Advanced Materials Interfaces}, volume = {12}, journal = {Advanced Materials Interfaces}, number = {1}, publisher = {Wiley}, issn = {2196-7350}, doi = {10.1002/admi.202400467}, pages = {9}, abstract = {AbstractThe chemical vapor deposition (CVD) growth of hexagonal boron nitride (hBN) on Ge substrates is a promising pathway to high-quality hBN thin films without metal contaminations for microelectronic applications, but the effect of CVD process parameters on the hBN properties is not well understood yet. The influence of local changes in pressure and temperature due to different reactor configurations on the structure and quality of hBN films grown on Ge(001)/Si is studied. Injection of the borazine precursor close to the sample surface results in an inhomogeneous film thickness, attributed to an inhomogeneous pressure distribution at the surface, as shown by computational fluid dynamics simulations. The additional formation of nanocrystalline islands is attributed to unfavorable gas phase reactions due to the radiative heating of the injector. Both issues are mitigated by increasing the injector-sample distance, leading to an 86\% reduction in pressure variability on the sample surface and a 200 °C reduction in precursor temperature. The resulting hBN films exhibit no nanocrystalline islands, improved thickness homogeneity, and high crystalline quality (Raman FWHM = 23 cm-1). This is competitive with hBN films grown on other non-metal substrates but achieved at lower temperature and with a low thickness of only a few nanometers.}, language = {en} }